Epoxidation of unsaturated polymers is well studied and has been reviewed (Rubber Chemistry and Technology, 1982, 55, 809). Epoxidation is widely used as a way to functionalize polymers by introducing oxirane groups which can be further converted to different functional groups. Peracides, particularly peracetic acid, have been used as the epoxidation agents. Peroxyformic acid has been used for the epoxidation of styrene-butadiene block copolymers (J. App. Pol. Sci. 1979, 23, 3301, & 3311). Similarly, cis-polyisoprene, butyl rubber, EPDM, and polybutadiene have been epoxidized (Polymer, 1983, 24, 107; J. Appl. Plym. Sci. Polm. Symp., 1977, 60, 47; Makromol. Chem., 1983, 184, 1153; Makromol. Chem., 1986, 187, 2761).
Functionalization of polyisobutylene-co-isoprene (butyl rubber) is of great interest due to its potential applications in technology areas such as surface modification, adhesion, drug delivery, compatibilization of polymer blends, and motor oil and fuel additives, and in providing clean cured products without contaminant leaching and/or side products.
Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 29, 547-553 (1991) reports the biphasic epoxidation of polyisobutylene-co-isoprene (butyl rubber) using H2O2 with a catalytic amount of methyltrioctylammonium tetrakis(diperoxotungsto)phosphate.
U.S. Pat. No. 5,789,512 covers a solution process for epoxidizing unsaturated polymers comprising reacting an unsaturated polymer with hydrogen peroxide in the presence of (a) tungstic acid or its metal salts, (b) phosphoric acid or its metal salts, and (c) at least one phase transfer catalyst.
WO2005063821A1 covers a solid-state process for producing an epoxidized elastomeric polymer comprising of feeding at least one elastomeric polymer containing ethylenic unsaturations to a mixing device, at least one hydrogen peroxide precursor, and at least one carboxylic acid or a derivative thereof and mixing and reacting in the presence of water.
US20080227922A1 describes a solution process for epoxidizing an ethylenically unsaturated isobutene polymer, in which an organic phase comprising the isobutene polymer is contacted with an aqueous phase which comprises formic acid and hydrogen peroxide. The process affords essentially quantitative conversions after short reaction time.
Conventional synthetic routes generate chemical wastes such as formic acid or metachlorobenzoic acid which have to be removed from the product and disposed of.
US 20050096480, and Angew. Chem. Int. Ed. 2003, 42, 5623-5625 entail a process for producing a 1,2-diol through reaction of an olefin with hydrogen peroxide in the presence of a polymer containing sulfo group. This disclosure is directed to small organic molecules, and does not provide any disclosure, teaching or suggestion that this process can be effective on elastomers.
The need exists for development of a method or process capable of producing epoxidized polymers with high efficiency by simple operation and/or by use of catalysts that can be recovered and reused.